The present invention relates to a method and apparatus for preparing pattern data for a machine tool which performs a desired work for a workpiece according to a desired pattern.
Among industrial machines, a machine such as sewing machine by which a desired stitch pattern is formed on a cloth automatically by moving the latter along a flat surface while holding the cloth with pressure, according to sewing data preliminarily programmed and stored in a memory device thereof is known. Such sewing data are usually stored in a recording medium in the memory device such that sewing of any of different patterns can be done easily. As the recording medium, semiconductor memory, magnetic card or floppy disc, etc., may be used, in which sewing machine operation information is stored according to the sequence of stitching. Control information for controlling the machine operation includes a control instruction concerning relative positional shift of the cloth to a needle of the sewing machine and a moving rate of the cloth for each stitching and a control instruction for controlling a motor for driving the sewing machine and the needle thereof. Control information for each sewing pattern is formed as a collection of these control instructions for each stitch. Therefore, in order to perform sewing of a desired sewing pattern with this sewing machine, it is necessary to prepare control data corresponding to the desired sewing pattern and store it on the recording medium.
FIG. 7 is a perspective view of an example of a conventional sewing data preparing apparatus which is disclosed in, for example, Japanese Kokai (Patent) No. 60-148582, FIG. 8 is a plan view of an example of a tablet digitizer thereof and FIG. 9 is an example of a hardware construction thereof. The tablet digitizer 10 (FIG. 8) is provided in front of the apparatus, which includes a menu portion 11 for inputting data and a pattern input portion 13.
In FIG. 7, a cursor 12 is used for selection on the menu portion 11 and acquisition of coordinate data from the pattern input portion 13. The sewing data preparing apparatus includes an LED display panel 20 including various switches and LED's provided on a front panel thereof and a CRT 26 for displaying pattern data, the CRT 26 being equipped with a usual key board 26A including ten keys and alphabetic keys, etc. The apparatus further includes a floppy disc driver 16 for driving a floppy disc 18 (FIG. 9) inserted thereinto as a recording medium to write sewing data into the floppy disc 18 or read it therefrom and a LED display panel 20.
In FIG. 7, the cursor 12 is shown together with an example of the menu portion 11. The cursor 12 includes a readout portion 12a and a switch 12b.
An operation of this sewing data preparing apparatus will be described with reference to FIG. 9. By drawing a desired sewing pattern on the tablet digitizer 10 using the cursor 12, sewing data is produced by control operations to be performed mainly by a CPU 14, which is temporarily stored in a RAM 24. Then, the temporarily stored data is written in the floppy disc 18 by the floppy disc driver 16 and the sewing machine 38 is driven by inserting the floppy disc 18 into the control device 40 as the sewing data recording medium.
In the conventional sewing data preparation apparatus mentioned above, the memory capacity of the apparatus for storing the sewing data depends upon a size of the RAM 24 and it is impossible to prepare sewing data whose size is larger than the capacity of the RAM 24.